Phase-controlled circuits are known which use electronic switches such as silicon controlled rectifiers (SCR's) or bilateral switches such as triacs, for automatically starting, regulating and stopping the operation of load devices such as discharge lamps. They are particularly favored for the regulation of high intensity discharge lamps such as metal halide and high pressure sodium lamps. Such circuits are described in U.S. Pat. Nos. 3,344,310-Nuckolls, Universal Lamp Control Circuit With High Voltage Producing Means and 3,500,124-Babcock, Discharge Lamp Control Circuit with Semiconductor Actuating Means Therefor.